/*

* Copyright (c) 2003 Nokia Corporation and/or its subsidiary(-ies). 

* All rights reserved.

* This component and the accompanying materials are made available

* under the terms of "Eclipse Public License v1.0"

* which accompanies this distribution, and is available

* at the URL "http://www.eclipse.org/legal/epl-v10.html".

*

* Initial Contributors:

* Nokia Corporation - initial contribution.

*

* Contributors:

*

* Description:  This file contains the header file of the Cmcn class.

*    

*                This header file presents an API which allows a client to

*                subscribe a number of CB topics from CbsServer. The client

*                receives a notification, if a message belonging to a subscribed

*                topic is received.

*

*/

#ifndef CMCN_H

#define CMCN_H

// INCLUDES

#include "e32base.h"

// CONSTANTS

// Maximum length of a MCN message.

const TInt KCbsMcnMessageMaxLength = 93;

// DATA TYPES  

typedef TBuf< KCbsMcnMessageMaxLength > TMcnMessage;

// FORWARD DECLARATIONS

class MCbsMcnObserver;

class CCbsMcnListener;

class RCbsMcnSession;

class CMcnTopicArray;

// CLASS DECLARATION

/**

*   Client must first connect to the server and then register 

*   a MCbsMcnObserver-derived class to receive notifications

*   when MCN messages are received from the network.

*

*   Registration to CbsServer is not required to retrieve

*   the current cell info message.

*    

*   In the example below, the client has implemented the class MCbsMcnObserver

*   in class CCbsMcnObserver. First, the client establishes a session

*   with CbsServer. The subscribed topics are specified with a CMcnTopicArray

*   instance. 

*

*   Example:

*

*   // Establish the session.

*   CMcn* session = CMcn::NewL();

*   CleanupStack::PushL( session );

*

*   // Specify topics with CMcnTopicArray.

*   CMcnTopicArray* topics = CMcnTopicArray::NewL();

*   topics->AddCbTopicL( 50 );      // District info (cell info)

*   topics->AddCbTopicL( 0 );       // CB index messages

*

*   // Register. Parameter observer is an instance of CCbsMcnObserver.

*   session->RegisterL( observer, topics );

*   delete topics;

*

*   // Get current MCN state.

*   TMcnMessage mcnInfo;

*   TInt result( session->GetCellInfo( mcnInfo ) );

*   if ( result != KErrNone )

*       {

*       // mcnInfo contains the current MCN message.

*       }

*   

*   // Observer's CellInfoChanged() gets called if MCN state changes.

*   // Note that the active scheduler must be running here.

*

*   // Terminate session.

*   session->Unregister( observer );

*   CleanupStack::PopAndDestroy(); // session, gets closed when deleted

*

*/

class CMcn 

    : public CBase

    {

public:             // New functions

    /**

    *   Instantiates new CMcn object and establishes a session with

    *   CBS server. 

    *   

    *   If connecting to CBS server fails, the function leaves with 

    *   the leave code of RSessionBase::CreateSession().

    *

    *   Active scheduler has to be installed prior to calling this function.

    *

    *   @return                     A new instance of CMcn

    */

    IMPORT_C static CMcn* NewL();

    /**

    *   Destructor. Also closes CbsServer session.

    */

    IMPORT_C ~CMcn();

    /**

    *   Registers an observer to CBS server. The observer is notified when

    *   a MCN message is received from the network.

    *   The caller is also required to provide an array containing numbers

    *   of subscribed topics.

    *

    *   Parameter aArray may contain topic number entry duplicates.

    *   Topics may be in any order.

    *

    *   Leave codes indicate an error accessing EPOC Telephony Sever.

    *   In this case, the leave code is the same returned by EPOC Telephony Sever.

    *

    *   @param  aObserver           Observer implemented by the client

    *   @param  aArray              List of relayed topics

    */

    IMPORT_C void RegisterL( MCbsMcnObserver* aObserver, 

        const CMcnTopicArray& aArray );

    /**

    *   Unregisters a previously registered MCN observer clearing

    *   any topic subscriptions of this client in CBS server.

    *

    *   Panics if the observer specified was not registered.

    *

    *   @param  aObserver           Observer implemented by the client

    */

    IMPORT_C void Unregister( MCbsMcnObserver* aObserver );

    /**

    *   Retrieves the current MCN message (Cell Info, topic 050) from CBS 

    *   server. A new MCN message always overwrites the previous one in CBS

    *   server, no buffering is done. Note that this function may be

    *   only used to retrieve cell info messages.

    *

    *   Return codes:

    *   KErrNone        aMcnMessage contains the current, valid MCN message.

    *   KErrNotFound    CbsServer has not yet received a MCN message.

    *                   Content of aMcnMessage must be ignored.

    *

    *   @param  aMcnMessage         Returns the current MCN message.

    *   @return                     Result code

    */

    IMPORT_C TInt GetCellInfo( TDes& aMcnMessage ) const;

private:    // new functions

    /**

    *   Default constructor.

    */

    CMcn();

    /**

    *   2nd-phase constructor

    */

    void ConstructL();    

    /** 

    *   Relays aMcnMessage to the registered observers.

    *   Used by a friend class CCbsMcnListener instance

    *

    *   @param  aMcnMessage         Received CB message from CbsServer    

    */    

    void RelayMessage( TCbsMcnMessage& aMcnMessage );    

private:    // friend classes

    /// Allows use of RelayMessageL().

    friend class CCbsMcnListener;

private:    // prohibited functions and operators 

    /// Copy constructor.

    CMcn( const CMcn& );

    /// Assignment operator

    CMcn& operator=( const CMcn& );

private:  // Data

    /**

    *   Own: Active object responsible for responding to server-initiated

    *   notification indicating that a message has arrived from

    *   the CbsServer.

    */

    CCbsMcnListener* iMcnListener;

    /// Own: Dynamic array containing the registered observers.

    CArrayPtrFlat< MCbsMcnObserver >* iObservers;

    /// CbsServer session object.

    RCbsMcnSession iSession;

public:

    /**

    *   Retrieves the current info message (e.g. HomeZone, topic 221) from CBS 

    *   server. A new info message always overwrites the previous one in CBS

    *   server, no buffering is done. Note that this function may be

    *   only used to retrieve cell info messages.

    *

    *   Return codes:

    *   KErrNone        aInfoMessage contains the current, valid info message.

    *   KErrNotFound    CbsServer has not yet received a info message.

    *                   Content of aInfoMessage must be ignored.

    *

    *   @param  aInfoMessage    Returns the current info message.

    *   @param  aTopicNumber    Number of the topic

    *   @return                 Result code

    */

    IMPORT_C TInt GetInfoMessage( TDes& aInfoMessage, TInt aTopicNumber ) const;

    };

#endif // CMCN_H

// End of File